在窗口打開時收到通知的最有效方式

Question

我正在編寫一個應用程序（.NET 4.0中的C＃和WPF），它需要打開窗口並關閉它們，如果它們不在它的白名單中。

到目前為止，使用來自User32.dll EnumDesktopWindows Windows API，我可以在我的機器上大約10毫秒內枚舉所有打開的窗口。 正如您現在可能已經猜到的那樣，我需要在很短的時間內盡快做到這一點，另一方面選擇較小的時間段會給系統帶來很大的開銷。

問題是，“打開窗口時是否有任何方法可以獲得通知（如使用事件）？無論哪種方式，最有效的方法是什么？

Answer 1

您可以使用RegisterWindowMessage和RegisterShellHookWindow API函數掛鈎到Shell以接收消息。

您將需要以下Interop導入：

public static class Interop
{
    public enum ShellEvents : int
    {
        HSHELL_WINDOWCREATED = 1,
        HSHELL_WINDOWDESTROYED = 2,
        HSHELL_ACTIVATESHELLWINDOW = 3,
        HSHELL_WINDOWACTIVATED = 4,
        HSHELL_GETMINRECT = 5,
        HSHELL_REDRAW = 6,
        HSHELL_TASKMAN = 7,
        HSHELL_LANGUAGE = 8,
        HSHELL_ACCESSIBILITYSTATE = 11,
        HSHELL_APPCOMMAND = 12
    }
    [DllImport("user32.dll", EntryPoint = "RegisterWindowMessageA", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
    public static extern int RegisterWindowMessage(string lpString);
    [DllImport("user32", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
    public static extern int DeregisterShellHookWindow(IntPtr hWnd);
    [DllImport("user32", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
    public static extern int RegisterShellHookWindow(IntPtr hWnd);
    [DllImport("user32", EntryPoint = "GetWindowTextA", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
    public static extern int GetWindowText(IntPtr hwnd, System.Text.StringBuilder lpString, int cch);
    [DllImport("user32", EntryPoint = "GetWindowTextLengthA", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
    public static extern int GetWindowTextLength(IntPtr hwnd);
}

為了能夠掛接到shell，您需要一個繼承自Form的類並重寫WndProc函數。 您可以使此窗體具有在窗口更改其狀態時將引發的事件。

public class SystemProcessHookForm : Form
{
    private readonly int msgNotify;
    public delegate void EventHandler(object sender, string data);
    public event EventHandler WindowEvent;
    protected virtual void OnWindowEvent(string data)
    {
        var handler = WindowEvent;
        if (handler != null)
        {
            handler(this, data);
        }
    }

    public SystemProcessHookForm()
    {
        // Hook on to the shell
        msgNotify = Interop.RegisterWindowMessage("SHELLHOOK");
        Interop.RegisterShellHookWindow(this.Handle);
    }

    protected override void WndProc(ref Message m)
    {
        if (m.Msg == msgNotify)
        {
            // Receive shell messages
            switch ((Interop.ShellEvents)m.WParam.ToInt32())
            {
                case Interop.ShellEvents.HSHELL_WINDOWCREATED:
                case Interop.ShellEvents.HSHELL_WINDOWDESTROYED:
                case Interop.ShellEvents.HSHELL_WINDOWACTIVATED:
                    string wName = GetWindowName(m.LParam);
                    var action = (Interop.ShellEvents)m.WParam.ToInt32();
                    OnWindowEvent(string.Format("{0} - {1}: {2}", action, m.LParam, wName));
                    break;
            }
        }
        base.WndProc(ref m);
    }

    private string GetWindowName(IntPtr hwnd)
    {
        StringBuilder sb = new StringBuilder();
        int longi = Interop.GetWindowTextLength(hwnd) + 1;
        sb.Capacity = longi;
        Interop.GetWindowText(hwnd, sb, sb.Capacity);
        return sb.ToString();
    }

    protected override void Dispose(bool disposing)
    {
        try { Interop.DeregisterShellHookWindow(this.Handle); }
        catch { }
        base.Dispose(disposing);
    }
}

然后，在您的應用程序的主要功能中，您可以擁有例如：

static void Main(string[] args)
{
    var f = new SystemProcessHookForm();
    f.WindowEvent += (sender, data) => Console.WriteLine(data); 
    while (true)
    {
        Application.DoEvents();
    }
}

輸出樣本：

Answer 2

使用System.Windows.Automation命名空間。

示例（取自舊新事物 ）等待特定進程打開對話框，然后解除它：

using System;
using System.Windows.Automation;
using System.Diagnostics;
using System.Threading;

class Program
{
    [STAThread]
    public static void Main(string[] args)
    {     
        Automation.AddAutomationEventHandler(
            WindowPattern.WindowOpenedEvent,
            AutomationElement.RootElement,
            TreeScope.Children,
            (sender, e) =>
            {
                var element = sender as AutomationElement;

                Console.WriteLine("new window opened");
            });

        Console.ReadLine();

        Automation.RemoveAllEventHandlers();
    }
}

Answer 3

如果您從其他應用程序訪問Windows，這不是一件容易的事，但您可以嘗試在Windows中使用Hook 。